Tianeptine, or 7-[(3-chloro-6-methyl-5,5-dioxo-11H-benzo[c][2,1]benzothiazepin-11-yl)amino]heptanoic acid, is an antidepressant with cognitive restorative effects. Investigators have reported that it can be used to treat post-traumatic stress disorder (PTSD) (Onder E. et al., (2005), European Psychiatry 21:174-179).
Although tianeptine shares structural similarities to classic tricyclic antidepressants, its pharmacological behavior is unique. More commonly known by the commercial names Stablon®, Coaxil, Tatinol, Tianeurax, and Salymbra, tianeptine is currently available throughout Europe, Asia, and Latin America for the treatment of depression. Tianeptine modulates the glutamatergic system and reverses the inhibitory neuroplasticity observed during periods of stress and steroid use. In modulating the glutamatergic system, tianeptine normalizes glutamate levels in the hippocampus, amygdala, and prefrontal cortex. Through genomic and non-genomic mechanisms, glutamate modulation restores plasticity, relieves inhibition of long-term potentiation, and reverses structural changes induced by chronic exposure to corticosteroids.
Tianeptine's anxiolytic properties and its reported ability to modulate the neuroendocrine stress response suggest that it can be used to treat PTSD. In fact, several studies have shown tianeptine to be an effective therapy for patients with PTSD because it is reported to improve many of the condition's characteristic symptoms (Crocq L & Gouj on C: The Anxio-Depressive component of the psychotraumatic syndrome and its treatment by tianeptine. Psychol Med, 1994; 26 (2): 192-214; Rumyantseva G M & Stepanov A L: Post-traumatic stress disorder in different types of stress (clinical features and treatment). Neurosci Behav Physiol, 2008; 38:55-61; and Frančišković, Tanja, et al. “Tianeptine in the combined treatment of combat related posttraumatic stress disorder.” Psychiatria Danubina 23(3) (2011): 257-263).
In addition to tianeptine's neuro-protective actions, including its ability to reverse the structural changes and inhibition of long term potentiation (LTP) caused by steroid exposure, it is reported to be potentially useful for treating neurocognitive dysfunction and similar side effects in patients treated with corticosteroids. Tianeptine's ability to restore cognitive functionality has also been observed in some animal models.
Due to their anti-inflammatory properties, corticosteroids are used in the treatment of many diseases and conditions including asthma, systematic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, nephritic syndrome, cancer, organ transplantation, autoimmune hepatitis, hypersensitivity reactions, cardiogenic and septic shock, glucocorticoid deficiency diseases (Addison's disease and panhypopituitarism), and multiple sclerosis. When the body experiences stress, the adrenal glands release corticosteroids, such as cortisol. Synthetic corticosteroids work by mimicking steroid hormones naturally produced by the adrenal glands. Upon release into the body's circulatory system, these hormones help to regulate inflammation as well as the body's immune response. Common synthetic corticosteroids include prednisone, cortisone, hydrocortisone, and methylprednisone. Supplementing the body's normal hormone levels with synthetic corticosteroids induces a genomic cascade that reduces inflammation and suppresses the immune response. This genomic cascade is initiated by the binding of steroids to intracellular glucocorticoid receptors (GRs) (Datson, N A et al. Identification of corticosteroid-responsive genes in rat hippocampus using serial analysis of gene expression. European Journal of Neuroscience. 2001; 14(4): 675-689).
Despite their widespread use and therapeutic benefit, synthetic corticosteroids often cause numerous adverse psychological, metabolic, and somatic side effects (Warrington T P, Bostwick J M. Psychiatric adverse effects of corticosteroids. Mayo Clinic Proceedings. 2006; 81(10)). Examples of such somatic side effects are displayed in Table 1. Psychological side effects include mood and anxiety disorders, behavioral disturbance, cognitive impairment, and psychosis.
TABLE 1Somatic Side Effects of Corticosteroid UseCardiovascularHypertensionAccelerated atherosclerosisDermatologicAcneAlopeciaHirsutismStriaeSkin atrophyPurpuraEndocrine/MetabolicObesityDiabetes MellitusAdrenal-pituitary axis suppressionHyperlipidemiaFluid and sodium retentionLoss of potassium, calcium, and nitrogenDelayed growthNeurologicPseudotumor cerebriGastrointestinalPeptic ulcer diseasePancreatitisFatty liverHematologicLeukocytosisNeutrophiliaLymphopheniaInfectiousOral candidiasisIncreased risk of systemic infectionMusculoskeletalMyopathyOsteoporosisAvascular necrosisOphthalmologicCataractsGlaucoma
Cognitive impairment, anxiety and mood disorders are among the most common psychological side effects of corticosteroid use. Especially for patients who require long-term steroid treatment, these effects result in a diminished quality of life. For example, 33% of individuals taking corticosteroids (about 13 million) are reported to exhibit deficits in working or short-term memory, declarative memory, attention span and concentration (academic & occupational performance), and executive functioning (Stoudemire A, Anfinson T, Edwards J. Corticosteroid-induced delirium and dependency. Gen Hosp Psychiatry. 1984; 141: 369-372). In extreme cases, steroids can even induce delirium, dementia (persistent memory impairment), and mania (Varney N R, Alexander B, Maclndoe J H. Reversible steroid dementia in patients without steroid psychosis. Am J Psychiatry. 1984; 141:369-372).
Currently, there is no FDA approved drug designated for the treatment of the cognitive impairment and similar psychiatric disorders, such as anxiety and mood disorders, associated with corticosteroid use. Tricyclic antidepressants do not appear to be useful therapeutic agents to modulate the psychiatric side effects induced by steroids, and may actually exacerbate these symptoms (Lewis D A, Smith R E. Steroid-induced Psychiatric Syndromes: A Report of 14 Cases and a review of the Literature. Journal of Affective Disorders. 1983; 5: 319-332). In addition, there are no alternatives to corticosteroids for the treatment of inflammatory disorders—corticosteroids must be used.
The disclosure herein relates to more stable chemical formulations, crystalline salts and polymorphs thereof of tianeptine for use in the treatment of neurocognitive dysfunction and related psychiatric disorders induced by corticosteroid treatment. These disorders include trauma- and stressor-related disorders including PTSD and acute stress disorder; depressive disorders including major depressive disorder, persistent depressive disorder, bipolar depression, and premenstrual dysphoric disorder; neurodegenerative diseases such as Alzheimer's disease and multi-infarct dementia; and neurodevelopmental disorders including attention-deficit\hyperactivity disorder. The present disclosure can also be used in the treatment of asthma and chronic obstructive pulmonary disorder.